An image processing apparatus such as a facsimile machine is commonly provided with an image sensor for reading an image, and a thermal printhead for recording an image which is received or read by the above image sensor on heat-sensitive paper for example.
If there is a reading/writing head capable of reading the image and recording the image on paper for the image processing apparatus, the facsimile machine will be assembled with fewer parts and components, the head will occupy a smaller space, and therefore the facsimile machine will be more compact.
Such a reading/writing head is already disclosed in the Japanese Patent Publication No. 6-319013. According to the reading/writing head disclosed in this publication, image sensing is achieved through an image reading surface provided at an upper surface of a casing, where light is reflected to pass through a rod lens array to focus on light receiving elements provided in an upper surface of an element-mounting substrate disposed in a bottom surface of a substrate. On the other hand, a thermal printhead function is achieved by an array of heating elements provided in a lower surface of a heating element formation substrate disposed adjacently to the element-mounting substrate on a bottom surface of a casing, whereas drive IC's for driving these heating elements are mounted on a lower surface of the element-mounting substrate.
However, the image reading/writing head according to the above arrangement has the following problems which must be solved.
First, the element-mounting substrate has one surface for mounting the light receiving elements for the image sensor, and the other surface for mounting the drive IC's for the thermal printhead. Because of such an arrangement, this element-mounting substrate is extremely difficult to manufacture. Specifically, this element-mounting substrate must be formed with a very fine wiring pattern in each of the two surfaces. Further, this element-mounting substrate must be mounted with elements by means of chip bonding and wire bonding in each of the two surfaces, and thus it is extremely difficult to smoothly perform such manufacturing operations today.
Second, the substrate for mounting the elements is prepared separately from the substrate in which the heating elements are formed. This increases the number of parts and assembling steps, raising cost of the image reading/writing head.
Third, the distance from the image reading surface to the light receiving elements is set to a so-called conjugated length of the rod lens array. This makes it impossible to further reduce the thickness of the head.
Fourth, the light receiving elements for the image sensor are separated from the drive IC's for the thermal printhead, raising the cost of the head.
It is therefore an object of the present invention to provide an image reading/writing head which can be manufactured more easily.
Another object of the present invention is to provide an image reading/writing head comprising a fewer number of parts.
Another object of the present invention is to provide an image reading/writing head having smaller outside dimensions.
Still another object of the present invention is to provide an integrated circuit suitable for the image reading/writing head.